Downlight and device for varying the spectral quality thereof



May 29, 1962 R. G WILLIAMS DOWNLIGHT AND DEVICE FOR VARYING THE SPECTRALQUALITY THEREOF Filed May 6, 1958 INV EN TOR. IPOLLO G/uE-sp/E MLL/AM6BY ma 544 United States 3,037,110 DOWNLIGHT AND DEVICE FOR VARYING TimSPEQTRAL QUALITY THEREGF Rollo Gillespie Williams, New York, N.Y.,assignor to Century Lighting, line, New York, N.Y., a corporation of NewYork Filed May 6, 1953, Ser. No. 733,314 1 Claim. (Cl. 24078) Thisinvention relates to a downlight and to a device for varying thespectral quality thereof.

A downlight is an electric lighting fixture which is mounted in aconcealed overhead position, as for instance in a ceiling, and hasassociated therewith an incandescent filament type light bulb and areflector for increasing the downward lighting efliciency of said bulb.

Although downlights are highly desirable and widely used because theyilluminate objects beneath them without the distractng effect of exposedfixtures and without taking up the space or requiring the cleaning thatexposed fixtures do, they have several drawbacks. For instance, since adownlight is concealed within, i.e., above, a ceiling, there is a greatcontrast in brightness between the spaces around the lights and theobjects beneath the lights which gives rise to a gloomy effect at theupper part of a room. Moreover, it is customary to equip downlights withuncolored light bulbs, that is to say, light bulbs having either clearenvelopes or white, frosted envelopes, so that the light cast thereby ispractically white, i.e. a very light yellow (white will hereinafter beconsidered to be the color quality of an incandescent filament at atemperature between 2700 and 3200 K.) inasmuch as this will yield themost desired illumination of objects beneath the same. However, thisstrong white beam at the ceiling very often is undesirable for the decorof a room or space. If the downlight is so constructed as to increasethe illumination near the ceiling, the presence of a white light at sucha high level creates a stark unattractive appearance. Moroever, throwingstrong white light from the fixture at such an angle as to decrease thegloom over the ceiling will distract passersby since light emanatingfrom a ceiling fixture at an angle less than 45 to the horizontal iswithin the normal range of vision of a person in the room.

It has been proposed, in order to avoid the foregoing difliculties, toincorporate a colored lens or filter in a downlight. This, however, hasthe drawback that it prevents white light from being cast on the objectto be illuminated and does not notably relieve the gloomy appearance ofthe ceiling. It also has been proposed to employ a colored envelope forthe lamp bulb but this, too, varies the desired spectral quality of thelight cast on the object below. Finally, it has been proposed to colorthe reflector. This does not alter the spectral quality of theunreflected light directed downwardly, but it does affect the spectralquality of reflected light and thus creates an eerie result.

It is an object of the present invention to provide a downlight whichavoids all of the foregoing difficulties and which, nevertheless,includes very few additional parts and, therefore, is only slightly moreexpensive,

It is another object of my invention to provide a downlight of thecharacter described in which the spectral quality of the direct andreflected strong light that is cast on an object beneath the same is notaltered, that is to say, is white, but further in which weak light beamsof an other than white spectral quality are cast at less than 45 to thehorizontal so as to relieve the gloom now present in the area of theceiling.

It is another object of my invention to provide a downlight of thecharacter described which has an unusual and attractive decor in thatthe weak high-level secondary illumination is of a spectral qualityother than Whi so that the ceiling and walls of a room are softlyilluminated in a desired color and yet the object which is to be lit bythe downlight is strongly bathed in- White light.

It is another object of my invention to provide a downlight of thecharacter described which has an uncolored bulb and reflector and yetwhich, when viewed by a passerby at an oblique angle, will appear to beother than white.

It is another object of my invention to provide a downlight having allof the foregoing desirable attributes and yet which has neither acolored bulb nor a colored reflector.

It is another object of my invention to provide a downlight of thecharacter described in which the spectral quality of the secondaryillumination can quickly and easily be varied at will to give anydesired color-accenting decorative effect.

Other objects of this invention will in part be obvious and in part willbe pointed out hereinafter.

The invention accordingly consists in the features of construction,combinations of elements, and arrangement of parts which will beexemplified in the construction hereinafter described, and of which thescope of application will be indicated in the appended claim.

In the accompanying drawings, in which is shown one of the variouspossible embodiments of this invention,

FIG. 1 is a schematic elevational view of an enclosed space such as aroom provided with downlights constructed in accordance with myinvention; and

FIG. 2 is a perspective view through one such downlight.

Referring now in detail to the drawings, the reference numeral 10denotes a downlight constructed in accordance with my invention. Saiddownlight includes a reflector 12, i.e., a hollow body, which provides asurface of revolution with a downwardly facing opening and the interiorsurface of which preferably is specular or semispecular and asillustrated is specular. A typical suitable material for this purpose isaluminum having, for instance, a polished interior surface. The specificcontour of the reflector will be described hereinafter. The upper end ofthe reflector is interrupted to provide an opening 1 from which an erecttubular sleeve 16 integrally extends. The top of said tubular sleeve hasmounted thereon an outlet box 18 in which there is secured a standardelectric socket 20 adapted to have held therein an incandescent electriclight bulb 22. A conduit 24 connected to the box is provided to pass apair of electric wires 26 that supply energy to the bulb. The envelopeof the bulb may be either clear or frosted, and in the form illustratedis frosted.

In general, the contour of the reflector is such, as is well known, thatall rays of light incident thereon will be cast in a generally downwarddirection. The particular reflector shown has a contour such that anyray of light emanating tangential to the surface of the envelope of thebulb will be principally reflected downwardly at an angle of 45 to thehorizontal as indicated at A. Within this cone light is nicely diffusedeither by utilizing a frosted bulb in combination with a specularreflector or a clear bulb in combination with a semispecular reflector.This particular 45 angle is arbitrarily chosen because it has beendetermined experimentally that a passerby, unless his attention isdistracted, ordinarily will not be annoyed by any bright object high onthe azimuth. 45 is best for this purpose; however, I contemplate the useof angles as great as 60. Accordingly, with the reflector-constructiondescribed, any ray of light emanating from the bulb and striking thereflector usually will not be observed by a passerby. It

will be apparent that if the tangential rays of light emanating from thebulb are reflected principally at an angle of 45, all other rays oflight emanating from the bulb and striking the reflector will bedirected downwardly at a steeper angle so that they will not ordinarilybe noticed by a person in the room below the light.

The downlight is mounted in a ceiling 28 having its lower end located inan opening 30 therethrough. The downlight can be secured in said openingin any suitable manner. For instance, I may provide a set of mountingtabs 32, e.g., four such tabs, equiangularly spaced around said openingand embedded in the plaster of the ceiling. Each of the tabs has securedthereto as by welding, an L-ring 34 having one vertical leg flush withthe opening in the ceiling and the other horizontal leg slightly abovethe exposed ceiling surface. The reflector portion of the reflector 12terminates at 36 a short distance above the ceiling line. From thislower termination zone 36 to the ceiling line the reflector is of anyarbitrary down wardly extending shape inasmuch as, as soon will be seen,this portion does not function as a reflector. The lower end of thereflector is provided with an outwardly protruding annular bead 38. Tosupport the reflector, and therefore the downlight, from the mountingmeans, the vertical leg of each L-ring has secured thereto, as bywelding, a U-shaped clip 40 of resilient strip metal. The head 38 isadapted to be disposed at the base of the U, the U being upwardlyextending and the base being lowermost.

The lower rim of the reflector is concealed by a cutoff plate 42 thebottom surface of which is flush with the finished ceiling line of theroom. Said cut-off plate is secured in position as by means of screws 44the heads of which engage the plate and are flush therewith and theshanks of which mesh with tapped bores in the horizontal legs of theL-rings. The cut-off plate has a central opening 46 through which thelight emanating from the downlight passes. Said opening is concentricwith the vertical central axi of the bulb and is of such size that itwill cut off all light issuing from the bulb and reflector and directeddownwardly at an angle less than 45 to the horizontal. In other words, aline drawn to the bulb from any point of the opening 46 and tangent tothe former at a diametrically opposite point on the envelope of the bulbwill be disposed at an angle of 45 Typical cut-off lines are indicatedby the reference numeral 48. It thus will be appreciated that thecombined effect of the reflector and cut-off plate is to create aprimary downwardly directed 90 cone of strong white light, the sides ofwhich are quite well defined. Heretofore it has been the practice tolimit illumination cast by a downlight to the aforesaid primary cone andfor this purpose to employ a black sleeve inside the reflector extendingdownwardly from the zone 36.

Pursuant to my invention, I provide a means for creating a secondaryregion of illumination above and around the primary cone, said regionbeing of a limited selectable visible spectral band, i.e. of a colorother than white. The aforesaid means constitutes a member 50 whichessentially comprises a multi-ring baflle the interior surface whereofis colored to provide a spectral reflectance of a limited selectedvisible spectral band. Typical spectral bands are 380/430, 431/470,471/510, 511/560, 561/595, 596/630 and 631/760 millimicrons, it beingunderstood that these ranges merely are exemplary and are not to beconstrued as limitative.

More particularly, the member 50 includes a cylindrical supporting ring52 the upper end of which is adjacent the zone 36, said zone being atthe intersection between the reflector and a 90 cone within and tangentto the central opening in the cut-off plate 42. The lower end of thering 52 is at about the level of the upper side of the cut-off plate.Said ring conveniently may be fabricated of sheet metal and in effectconstitutes a largediameter squat sleeve. Projecting inwardly of thesleeve are a series of baffle plates 54, 56, 58. The baffle plates canbe secured to the sleeve in any suitable manner. For instance, thesleeve can be formed with a series of vertically spaced internal annulargrooves and the outer peripheries of some or all of the baffle platescan be placed in and secured as by crimping to the sleeve. The lowerbaflfle plate simply may lie against an Out-turned flange 60 at thebottom of the sleeve and be permanently attached thereto as by welding.

Each of the baflle plates provides a large central opening 62 arrangedsymmetrically about the vertical central axis of the electric light bulb22 so that all of the openings of the baffle are concentric in plan. Inthe preferred form of my invention, the baffle openings areprogressively smaller in a downward direction; that is to say, theuppermost baflle 54 has the largest opening, the lowermost bafile 58 hasthe smallest opening, and the intermediate baflle 56 has an opening thesize of which is intermediate that of the openings in the upper andlower baffles. Desirably, the openings vary proportionately to thespaces between the baflles so that a diametrical line drawn from theinner edge of any one of the baifle openings and touching any otherinner edge of another baffle opening will touch the inner edges of allthe baflle openings. Moreover, it is preferred that the central openingin the cut-off plate be slightly smaller than the opening in thelowermost baflle plate.

The lowermost baffle and the entire member 50 simply rest on the ceilingplate. Inasmuch as said member fits with comparative snugness in thelower part of the reflector, there is no tendency for it to move about.However, this arrangement enables the member 50 to be easily replacedmerely by removing the screws 44, dropping the cutoff plate, taking outsaid member and replacing it with another having a different spectralreflectance band. The inner surface of the sleeve 52 and all exposedsurfaces, i.e., both upper and lower surfaces and the edge of theopening, of all the baffles except the lower surface of the lower baflleare of the same spectral reflectance band, the same having been impartedthereto in any convenient fashion, as by spraying a colored paintthereon. The finish of the battle is not of critical importance; forexample, the baffle either can be diffuse, semi-diffuse or shiny,depending upon the desired decorative effect.

When in the operation of a downlight embodying my invention the electriclight bulb 22 is energized, all of the light emanating therefrom in adirection downwardly through the opening in the ceiling plate will bewhite. Moreover, all of the light emanating from the bulb and strikingthe reflector, and after leaving the reflector, passing through theopening in the cut-off plate either immediately or upon furtherreflection with the reflector likewise will be uncolored so that theprimary cone of strong light will be white and will bathe in white lightany object disposed therebeneath. All other light emanating from thebulb or reflector either will be trapped in the sleeve 16 or will atsome point in its travel strike the member 50; thus some of the lightwill strike the upper surfaces of the balfle plates and be reflectedfrom there back up to the reflector after which it will eventually andat least in large part pass through the opening in the cut-off plate.Other rays of light emanating from the light bulb will strike theinterior surface of the sleeve 52 and ultimately, upon furtherreflection in part with other surfaces of the member 50, also passthrough the opening in the cut-off plate. All of these rays of lightwhich at some point in their travel have impinged upon and beenreflected from the member 50 will be colored. Moreover, these rays oflight will issue from the downlight principally at an angle less than 45to the horizontal. It will be apparent that reflection from the surfaceof the member 50 will vary depending upon the specific type of finish. Ihave indicated in FIG. 2 at B one type of reflection, this being thetype created by a semi-diffusing finish in which there is diffusion ofeach ray of light that impinges upon any part of the surface, but themajor strength of light radiating from the surface as a result ofimpingement of a beam of light thereon will be in the direction of aspecularly reflected beam. Other light issuing from the point ofimpingement will be at spread angles but of lesser strength. However,regardless of the angle at which the light is reflected, it will be seenthat the principal portion of the light which has been colored byimpingement on the member 50 will issue from the downlight at an angleless than 45 to the horizontal.

It will be appreciated that practically all of the light which iscolored is at least secondarily reflected; that is to say, it will bethe result of at least two reflections against colored surfaces, so thatthe colored light issuing from the downlight will be comparatively softin quality, i.e., not glaring, but rather mild, this being a desiredattribute of the more nearly horizontal light rays. It will beunderstood, of course, that many of the reflections will be the resultof tertiary or additional reflections and, therefore, will be stillweaker. Moreover, the major proportion of the surface of the member 50which can be seen by deliberate observation will be at least secondarilyilluminated and, therefore, not so strongly illuminated as to create anunpleasant and distracting glare.

It also will be observed that the reflector itself will ap pear to becolored. This is due to the fact that unless one is deliberately staringat the reflector it will not be noticed except at an angle less than 45,and all light issuing from the reflector at an angle of less than 45 tothe horizontal is colored and mild. Moreover, since all of this light iscolored, the reflector itself will seem to be colored. Indeed, whatactually is seen in the reflector are images of the upper surfaces ofthe baflle plates and, therefore, are colored objects. This has theeffect of seeming to paint the reflector with the color employed so thatthe glow which is present at the ceiling in the vicinity of thedownlight is of the color of the spectral band utilized and not white asit is in the case of an ordinary downlight. This is true despite thefact that the light which illuminates objects beneath the downlight isas white as the light which the electric light bulb 2.2 is capable ofcasting.

The overall effect of employing several downlights such as described canbest be seen in FIG. 1. It will be observed that each downlight casts aprimary cone 64 of strong white light downwardly within an angle of 45to the horizontal. Moreover, due to the use of the member 50 inaccordance with my invention, each downlight further creates a soft,i.e., mild, secondary region 66 of light at an angle of less than 45 tothe horizontal so that near the ceiling the space between the downlightsis illuminated in the desired spectral band and is not left gloomy asheretofore. Moreover, this color is of any desired spectral band despitethe fact that objects beneath the downlight are illuminated 'with whitelight. It may be mentioned that some weak colored light stray into thecone 64 of each downlight. However, this incidental colored light willbe washed out and rendered unnoticeable by the intense white light inthis region.

By way of example, in a downlight having a lower opening about 11%" indiameter and a cut-ofl plate having a 6" opening, the opening in thelower baflle plate likewise is approximately, although slightly morethan, 6", the opening in the intermediate baflle plate is 8%",

and the opening in the uppermost baffle plate is 9 The space between theintermediate and lower baflie plates is 1% and the space between theintermediate and upper baffle plates is A of an inch. The height of thesleeve 52 is 2%. These dimensions have been given to facilitate theunderstanding of my invention, and the embodiment thereof in practicalcommercial structures. They are not, however, intended to be alimitation upon the scope of the invention.

It will thus be seen that there is provided a device in which theseveral objects of this invention are achieved, and which is welladapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention,and as various changes might be made in the embodiment above set forth,it is to be understood that all matter herein set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.

Having thus described the invention, there is claimed as new and desiredto be secured by Letters Patent:

In combination with an above-the-ceiling downlight including anuncolored incandescent electric light bulb and an uncolored reflectorseparat from the bulk and symmetrically disposed around the same andhaving an open lower end through which is emitted a cone of light of thespectral quality of the light radiated by the bulb, means to support thereflector and bulb above the ceiling, the reflector being shapedprincipally to reflect downwardly at less than a predetermined angle alllight incident thereon from the light bulb, means for varying thespectral quality principally of the light issuing therefrom at an angleabove said predetermined angle, said last-named means comprising aunitary assembly located in and adjacent the open end of the reflector,said assembly including a sleeve and plural annular flat baflles jointlycarried by the sleeve and extending inwardly thereof perpendicular tothe axis of symmetry of the reflector, the lowermost baffle beingarranged for disposition at substantially the ceiling line, saidassembly thereby defining an opening, a substantial portion of saidreflector being visible through the opening of the assembly above theuppermost baflie and laterally outwardly of the bulk, at least theinternal surface of the sleeve, the upper surface of the lowermostbaflle and the upper and lower surfaces of the remaining bafltles havinga semi-diflusing finish and being of a common limited visible spectralband Within the range of from 380 to 760 millimicrons and being sodisposed and arranged with respect to the reflector and the bulb as toreflect back to the reflector light incident thereon and colored by thesaid surfaces whereby to create in the zone above the cone of light andbelow the ceiling a range of secondary illumination in a color otherthan white and thereby also apparently to color the reflector as viewedwithin said zone, and means independent of the reflector and bulbsupporting means for rapidly detaohably securing said assembly to theceiling.

References Cited in the file of this patent UNITED STATES PATENTS2,078,986 Young May 4, 1937 2,179,161 Ram-busch et al Nov. 7, 19392,465,248 McCandless Mar. 22, 1949 2,640,148 McCandless May 26, 1953

